The present invention relates to a power steering system or apparatus, and/or a power steering control method, and more specifically to a motor-driven hydraulic power steering system.
A power steering system is arranged to produce a power assisting force (steering assist force) with a hydraulic power cylinder by a flow control valve in accordance with an operation of a steering wheel. A Published Japanese Patent Application Publication No. 2002-145087 shows a power steering system including an opening/closing solenoid valve disposed in a connection passage or bypass passage connecting left and right circuit sections. This solenoid valve is a normally open valve which allows a normal power steering operation by closing the connection passage when energized, and which opens the connection passage to enable a manual steering operation when the solenoid valve is not energized.